Chromosome study of 85 patients with myelodysplastic syndrome.

We studied bone marrow chromosomes in 85 consecutive patients with myelodysplastic syndrome (MDS). Fifty-seven (67%) had a clone with an abnormal karyotype at diagnosis. Eight had secondary MDS, all with abnormal karyotypes. The frequency of abnormal karyotypes in the primary MDS was 64.9%. During subsequent follow-up, five patients acquired chromosome abnormalities; thus, at the end of the study, 72.0% of patients had an abnormal karyotype. The most frequent chromosome abnormalities were 5q-, +8, -7, -5, and -22. Forty patients (i.e., 70% of those with an abnormal karyotype and 47% of the whole group) had one of the karyotype abnormalities associated with secondary MDS or acute nonlymphocytic leukemia; in other words, 5q- or -5, or -7. Of all patients, 21.1% progressed into ANLL. Unfavorable prognostic factors associated with the risk of evolution into ANLL and with shorter overall survival were the presence of greater than 5% of bone marrow blasts, major chromosome abnormalities, and monosomy 7.